Atomic and molecular masses

Having introduced the ideas of atoms and molecules, it is worth pausing to define precisely what is meant by 'atomic mass' and 'molecular mass'. Because an actual atom or molecule is far too small to weigh directly on any real balance (a single hydrogen atom, for instance, has a mass of only about 1.6736 x 10^-24 g), chemists instead express these masses on a convenient RELATIVE scale — comparing how heavy one atom …